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Pulmonary Embolism: The Danger of Blood Clots

Pulmonary Embolism: The Danger of Blood Clots

The human body can’t survive without blood. Blood plays the important roles of bringing oxygen and nutrients to the body, transporting waste, and fighting off infections. It is able to go to the organs it needs to through the veins, which allows the blood to circulate throughout the body. And at the center of this complex operation is the heart, which is responsible for pumping the blood.

A blood clot can spell trouble for the circulatory system, as it can travel throughout different parts of the body. A pulmonary embolism occurs when a clot reaches the lungs — a life-threatening disease if not treated immediately.

Learn more about pulmonary embolism, particularly its causes, symptoms, risks, and prevention.

What Is Pulmonary Embolism?

Pulmonary embolism (PE) occurs when a clot or blockage makes its way to the pulmonary arteries, which are arteries located in the lungs. The pulmonary artery transports oxygen-poor (deoxygenated) blood from the heart to the lungs, where it becomes oxygen-rich (oxygenated) blood ready for use.

When a blood clot forms, blood thickens and forms a mass that blocks the veins. Once a clot causes pulmonary embolism, it can greatly impair the function of the lungs to make oxygenated blood.

PE can be life-threatening especially if several clots have blocked the pulmonary arteries or if a particular clot is large. PE can also cause the following:

  • Damage to the lungs may be permanent.
  • Low oxygen levels in the blood or hypoxemia (in severe cases, this can affect brain and heart function).
  • Organ failure or damage from lack of oxygen in the blood.

Most cases of PE result from a clot formed in the deep veins located in the lower extremities. This condition is known as “Deep Vein Thrombosis” (DVT). Clots formed in the deep veins of the leg, calf, or thigh may travel to the arteries of the lungs through the bloodstream.

What You Should Know About Deep Vein Thrombosis

In PE, usually multiple clots block different arteries of the lungs. Without blood, some areas of the lungs linked to the blocked arteries may die resulting in a lack of oxygen in the body.

Sometimes, other things besides blood clots cause blockages in blood vessels like the arteries or veins. Blood vessels can also be blocked by:

  • Air bubbles
  • Fat
  • Cancer cells
  • Amniotic fluid
  • Foreign substance

Who Is at Risk of PE?

Anyone can get PE, however some risk factors may increase a person’s risk. Risk factors of Pulmonary Embolism are the following:

  • Being inactive: People who are immobile for long periods of time may be at risk of blood clots that can lead to PE. People who have to undergo bedrest because of surgery are at risk because the flow of blood slows down when the legs are horizontal for long periods. This can make bedridden people more at risk of blood clots.

    Similarly, those who are travelling by air or by land for longer periods of time are also at risk of blood clots because they’re usually cramped in a seat for the duration of the trip.
  • Having a heart disease: Heart diseases like heart failure or other cardiovascular conditions can make you more at risk of developing blood clots that can cause PE.
  • Some types of cancer: Cancer of the brain, kidneys, colon, ovary, pancreas, stomach, or lung can put you at risk of PE because these cancers can spread to other parts of the body. Radiation treatment like chemotherapy also increases a person’s chances of developing blood clots.
  • Coronavirus disease 2019: A person with COVID-19 may be at risk of PE. Data has suggested that severe cases of COVID-19 can cause abnormal blood clotting.
  • Pregnancy or birth: Pregnant women are more at risk of developing deep vein thrombosis (DVT) due to reduced blood flow to the legs. The risk of PE is greatest six weeks after birth.
  • Smoking: Smoking has been shown to make a person more at risk of developing blood clots.

Other risk factors for PE include:

  • Obesity
  • Taking birth control or hormone replacement therapy
  • Age
  • Genes or family history

What You Need to Know About Blood Clotting Disorders

Signs and Symptoms of Pulmonary Embolism

Symptoms of PE can vary depending on factors like the size of the clot, how many clots are present, and pre-existing conditions. PE can be life-threatening so if you feel suddenly out of breath with a pain in the chest, it’s best to immediately contact emergency health services.

Signs and symptoms of pulmonary embolism are:

  • Skin that appears to be bluish
  • Feeling faint or lightheaded
  • Feeling sweaty
  • Increased heart rate
  • Coughing up sputum with blood
  • Irregular heartbeat
  • Having difficulty breathing
  • Chest pain
  • Swelling of the legs

Small emboli may not cause any symptoms, but when symptoms do occur, they often develop abruptly. The most common signs and symptom in pulmonary embolism is shortness of breath, chest pain and light-headedness. This is why it’s important to consult with your doctor if you suspect that you have blood clots that need to be checked out.

Prevention of Pulmonary Embolism

The prevention of pulmonary embolism involves making lifestyle changes and taking extra precautionary measures that can help prevent blood clots from occurring in different parts of the body. If you want to reduce your risk of PE, try the following:

  • Travel safely: If you’re going to be going on a long trip, make sure to stay hydrated as dehydration increases your risk of developing blood clots. Make sure to move your legs or shift position if you’re going to be seated for a long period.
  • Blood Thinners: If you’ve been hospitalized for stroke or heart attack then you may be given blood thinners to reduce your risk of developing blood clots.
  • Stay active: It’s especially important to still get ample amounts of physical movement especially if you’ve recently had surgery. Taking a short walk around the room or even just moving your legs will reduce the risk of DVT which can lead to pulmonary embolism.
  • Quit Smoking: Smoking has been proven to cause blood clots. Quitting may also improve your overall health.


Pulmonary Embolism (PE) results from one or more clots blocking the pulmonary arteries in the lungs. PE can be life-threatening if not treated because blocked pulmonary arteries can significantly reduce the amount of oxygen in the body. If you feel suddenly out of breath accompanied by chest pain, contact emergency health services immediately.

Learn more about Blood Disorders here.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Written by Ruby Anne Hornillos Updated Jun 09
Medically reviewed by Jobelle Ann Dela Cruz Bigalbal, M.D.